In key telephone systems the line control boards have handles positioned along the edge opposite the terminals for the purpose of providing gripping surfaces for removing the printed wiring board from the network. Typically, the handles are provided with electrical terminals which can be interconnected in various combinations to provide different operational characteristics for the associated line circuit.
Because of the universal nature of the line boards the option connections must be easily changeable. This has been accomplished in the past by using a series of terminals to which wires may be attached and by cross-connecting the wires between the terminals to provide the required circuit parameters. Such an arrangement has the drawback that some degree of skill is involved in changing options. In addition, the wiring terminals are located on the inside of the handle away from the view of the craftsperson and thus, in order to ascertain which options are currently associated with a line board it is necessary to remove the line board from the network.
Thus, it is desired to construct a key telephone circuit board having easily determinable and easily changeable options while at the same time preventing the accidental change of the established options.